Field of the Invention
The present invention relates to an optical touch display device, and more particularly, to an optical touch display device which is advantageous in high-speed driving, large-area touch sensing, and multi-touch sensing because of use of an image map and which can improve touch sensing performance and a driving method thereof.
Discussion of the Related Art
Instead of a mouse or a keyboard which was used as an input unit of a flat panel display device in the past, a touch screen device in which a user can input information directly to a screen using a finger or a pen has been used.
A touch screen device is applied to monitors of a navigation apparatus, an industrial terminal, a notebook computer, banking automation equipment, a game machine, and the like; portable terminals such as a mobile phone, an MP3, a PDA, a PMP, a PSP, a portable game machine, a DMB receiver, and a tablet PC; and household electrical appliances such as a refrigerator, a microwave oven, and a washing machine, and has been used more widely with a merit that it can be easily manipulated by any one.
Various types of touch screens have been developed and used such as a resistive type, an electro-magnetic type, an infrared type, and a capacitive type.
FIG. 1 is a diagram schematically illustrating an infrared type touch screen device according to the related art.
Referring to FIG. 1, the infrared type touch screen device according to the related art includes an infrared LED disposed on one side surface of a waveguide formed of reinforced glass or plastics, a projector disposed under the waveguide and configured to emitting a display beam, and an infrared camera disposed under the waveguide.
When a user touches a screen displayed on the entire surface of the waveguide, infrared rays totally reflected in the waveguide are refracted to the bottom of the waveguide and the infrared rays are received using the infrared camera, whereby the touch is sensed. At this time, an angle at which the infrared rays are sensed is calculated to detect a touched position.
Since such an infrared type touch screen device has to include the infrared camera, there is a problem in that the number of manufacturing processes and the manufacturing costs increase and the size and thickness of the device increase.
Capacitive type touch devices can be classified into an in-cell type in which a touch device is incorporated in cells of a display panel, an on-cell type in which a touch device is formed on a display panel, and an add-on type in which a touch screen is particularly coupled to the top of a display device. In recent years, the in-cell type touch screen having a merit in beautiful design and slimness has been used more and more.
FIG. 2 is a diagram schematically illustrating an in-cell type touch display device according to the related art.
Referring to FIG. 2, the in-cell touch type display device according to the related art includes a display panel, a gate driver (not illustrated), a data driver (not illustrated), and a touch driver (not illustrated).
Plural sub-pixels are formed in the display panel, and a touch screen is formed by plural touch electrodes 10. Here, the touch electrodes 10 are formed in the display panel 1 along with the sub-pixels. Common electrodes formed to supply a common voltage Vcom to the sub-pixels are used as the touch electrodes 10.
The plural touch electrodes 10 include plural drive electrodes 12 (TX electrodes) supplied with a touch driving signal (TC signal) and plural reception electrodes 14 (RX electrodes) for sensing a touch. The plural reception electrodes 14 can be formed in the form of single wires to have a bar shape from the upper end to the lower end of the display panel 1. The plural drive electrodes 12 can be grouped by a predetermined number of pixels.
Plural drive electrode lines 20 supplying a touch drive signal to the plural drive electrodes 12 are formed in the display panel 1. The plural drive electrodes 12 formed in the same horizontal line are connected by the drive electrode line 20. In addition, plural reception electrode lines 30 sensing capacitance of the plural reception electrodes 14 are formed.
The touch driver includes a touch driving integrated circuit (IC) and a touch sensing integrated circuit (IC). The touch driving IC is connected to the plural drive electrode lines 20 to supply a touch driving signal to the plural drive electrodes 12. The touch sensing IC is connected to the plural reception electrode lines 30 to senses a touch signal.
In such an in-cell touch type display device according to the related art, since the plural drive electrode lines 20 and the plural reception electrode lines 30 have to be formed to cross each other in order to use common electrodes in the display panel as the touch electrodes 10, there is a problem in that the number of manufacturing processes increases.
In the in-cell touch type, the drive electrodes 12 and the distance between the electrodes is small because the reception electrodes 14 are formed on the same plane, and parasitic capacitance increases because the plural drive electrode lines 20 and the plural reception electrode lines 30 are formed in cells. There is a problem in that the larger of the screen of the display panel becomes, the greater the parasitic capacitance becomes geometrically and the sensing performance of the touch sensing IC is lowered when the parasitic capacitance becomes greater. Accordingly, an increase in size of the in-cell touch type display device is restricted.